Transition metal complexes with thiosemicarbazide-based ligands. Part 51. Square-planar nickel(II) complex with acetylacetone bis(S-n- propylisothiosemicarbazone) (L). Crystal and molecular structure of [Ni(L-H)]NCS and two isomorphic complexes [Ni(L-H)]I·EtOH and [Ni(L-H)]I·iPrOH

Abstract

The template reaction of a warm methanolic solution of Ni(OAc) 2·4H2O, S-n-propylisothiosemicarbazide hydroiodide and acetylacetone yielded the needle-like, brown, diamagnetic complex [Ni(L-H)]I·MeOH, and in the presence of an excess of NH4NCS, brown, prismatic crystals of the complex [Ni(L-H)]NCS (1), both compounds involving the monoanionic form of the ligand, acetylacetone bis(S-n- propylisothiosemicarbazone), L. Slow recrystallization from MeOH, EtOH, iPrOH and Me2CO gave the corresponding monosolvent complexes [Ni(L-H)]I·solvent, of which only those involving EtOH and iPrOH were suitable for structural analysis. The crystallographic parameters of [Ni(L-H)]I·EtOH (2) and [Ni(L-H)]I·iPrOH (3) are very similar to each other, showing their structures are isomorphic. The crystal structures of the title compounds consist of the independent ions: NCS-, or I -, and the chemically identical cation [Ni(L-H)]+, where L-H is the monoanion resulting from deprotonation of the acetylacetone moiety, a tetradentate N4 ligand forming a square-planar coordination around a Ni(II) ion. It was found that the isothiosemicarbazide fragment of the ligand has an imido form. The complex cations of the compounds [Ni(L-H)]NCS and [Ni(L-H)]I·EtOH exhibit significant difference only in the conformation of their propyl groups.